Lasers with short pulse duration with high beam quality are very useful for many applications that require high brightness (e.g. material removal for micro-machining, x-ray generation, efficient non-linear processes, etc.). The most common method for generating short pulses in solid state lasers is a method known as Q-switching. The pulse duration of a conventional Q-switched lasers range from .about.5 ns to .about.200 ns. These pulses can be further shortened using a high gain, very short resonator. Using such methods can generate sub nanosecond pulses at micro-Joule level. Mode locking is another known method for generating short pulse duration. In mode locked lasers the pulse duration can be generated in a variety of ranges, for example .about.100 fs to .about.300 ps. Mode locked lasers generate continuous or semi-continuous pulse trains, and the energy per single picosecond pulse is on the order of nano-Joule. Many applications require energy per pulse (not pulse train) in the range of .about.1 to .about.300 mJ;. therefore, the above methods require beam amplification in the range of .about.10.sup.3 to .about.10.sup.8. Regenerative or multi-stage amplification can provide the high gain, but such amplifiers are very expensive and/or complex for practical commercial systems.
From the above, it is apparent that there is a need for a better laser system for producing a very short pulse duration at a mJ/pulse energy level.